Utah EHV-1: Case Count Stands at Seven

(Editor's Note: Article has been adjusted to reflect updated information provided by the Utah state veterinarian's office.)

The Utah state veterinarian's office has now confirmed seven equine herpesvirus-1 (EHV-1) cases, according to a March 6 statement.

"The state veterinarian's office is restricting the movement of the animals at eight locations in Cache County as a precaution to prevent the spread of the disease," the statement read. "The outbreak remains confined to Cache County, as there have been no other reports of EHV-1 symptoms in horses in other areas of the state. Nonetheless, horse owners throughout Utah are advised to take extra biosecurity precautions when taking their animals to shows or public arenas."

The outbreak began Feb. 26 when two horses tested positive for the disease; two additional horses were confirmed to be EHV-1 positive the following day. On March 4, officials announced that two more horses had tested positive for the disease. Two of the eight EHV-1 positive horses have been euthanized as a result of the disease; the remaining animals are being treated and are under veterinary care, the statement read.

The statement also noted that the Cache County Fairgrounds Horse Arena has closed until further notice because most of the horses had been at the facility recently. "Horse owners who have taken their animals to the Cache County Fairgrounds Arena during the past 30 days should monitor their horse's temperature and report concerns to their local veterinarian," the statement read.

"The state veterinarian recommends that horse facilities proceed with planned equine events, and that horse owners planning on traveling to an event should take their horse's temperature daily, beginning three days prior to travel and daily during the event," the statement read. "Horses with temperatures of 103°F and above should not travel or mingle with other horses. Horses should be isolated for two weeks after returning home from an event, during which time they should be monitored for disease symptoms."

Statewide, no other horses have shown signs of EHV-1; however, the state veterinarian's office is advising Utah horse owners to take extra security measures to prevent unnecessary contact with possibly infected horses and to quickly report clinical signs to their veterinarian.

EHV-1 is a highly contagious infection that can cause respiratory disease in weanlings and young horses, abortion in pregnant mares, and neurologic disease in adult horses.

Fever, cough, decreased appetite, depression, and a nasal discharge are the most common signs of EHV-1 infection in young horses. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around 8 months), but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1. In many horses, fever is the only sign of EHV-1 infection, which can go undetected.

Signs of the neurologic form of EHV-1 (often called equine herpesvirus myeloencephalopathy, or EHM) are variable, depending on where in the brain and spinal cord the virus has damaged the blood vessels. Horses with EHM usually have a fever at the onset of the disease. A few days later, neurologic signs such as ataxia (incoordination), bladder atony (urine retention, dribbling), loss of tail tone, and recumbency (inability to rise) develop.

TheHorse.com will continue to provide updates as more information becomes available.

About the Author

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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